Can get 'spoke protectors' at Loose Screws:
http://www.loosescrews.com/index.cgi...d=735102611785

Shimano at Jensen and bikeman:
http://www.jensonusa.com/store/produ...s.aspx?sc=FRGL
http://www.bikemannetwork.com/biking/c/COMPCASSSPROTEC

Pretty easy to find what you need or just go down to your local LBS and they can sell you one. Just be sure you get the right one...some are for freewheel setups...and can come in different diameters depending your largest gear. The old school metal ones are hard to find, but seems to be a desirable item for those that like that look.